1. Field of the Invention
This invention relates to elastomeric material covered rolls for use in various fields of industry, such as papermaking, ironmaking and textile manufacture. More particularly, it is concerned with an elastomeric material covered roll adapted for use under a heavy load at a high speed of rotation, and comprising a metallic roll core, a reinforcing layer of at least one nonwoven fabric impregnated with a thermosetting resin and a fine inorganic powder and surrounding the roll core, and a layer of elastomeric material, such as polyurethane rubber, surrounding the reinforcing layer. This invention also relates to a method of making those rolls.
2. Description of the Prior Art
There is known a roll comprising a roll core, a reinforcing layer of fibrous yarns impregnated with a thermosetting resin, such as an epoxy or unsaturated polyester resin, and wound around the roll core, and a polyurethane rubber layer formed around the reinforcing layer by casting, as disclosed, for example, in Japanese Patent Publication No. 19814/1973. The reinforcing layer, however, contains a relatively small proportion of the thermosetting resin, which is only about a half in weight of the fibrous yarns. Therefore, the reinforcing layer has a low compressive strength leading to a low surface strength of the polyurethane rubber layer. The fibrous yarns extend in parallel to the circumference of roll core, or at an angle thereto. When the roll is rotated at a high speed under a heavy load, the reinforcing layer is likely to crack along the fibrous yarns, and the cracks grow easily, resulting in the breaking of the reinforcing layer.
Particularly, if such breaking of the reinforcing layer occurs in the vicinity of its boundary with the rubber layer, the rubber layer cannot remain fixed firmly, but often comes off the roll core. Thus, the durability of the known roll is far from being satisfactory. For example, when a roll having a reinforcing layer of the nature as described above was rotated at a speed of 200 rpm under a load of 200 kg/cm.sup.2, the reinforcing layer had a broken surface after 20 to 30 hours, resulting in the stripping of the rubber layer.
It has also been proposed to use a cloth of fibers impregnated with a resin instead of, or in addition to the aforementioned resin impregnated fibrous yarns (U.S. Pat. Nos. 3,490,119, 3,520,747 and 3,646,651, and Japanese Patent Publication No. 39869/1972). These rolls are, however, unsatisfactory, too, in durability and other aspects.